ASTM E3375-23

This international standard was developed in accordance with internationally recognized principles on standardization established in the Decision on Principles for the
Development of International Standards, Guides and Recommendations issued by the World Trade Organization Technical Barriers to Trade (TBT) Committee.
Designation: E3375 − 23
Standard Practice for
Cone Beam Computed Tomographic (CT) Examination
This standard is issued under the fixed designation E3375; the number immediately following the designation indicates the year of
original adoption or, in the case of revision, the year of last revision. A number in parentheses indicates the year of last reapproval. A
superscript epsilon (´) indicates an editorial change since the last revision or reapproval.
1. Scope 2. Referenced Documents
1.1 This practice establishes the minimum requirements for 2.1 ASTM Standards:
computed tomography (CT) examination of components using E543 Specification for Agencies Performing Nondestructive
cone beam systems. The purpose of this practice is to establish Testing
instruction, procedures, and equipment qualification to inspect E1316 Terminology for Nondestructive Examinations
a component for specified discontinuities. E1441 Guide for Computed Tomography (CT)
E1672 Guide for Computed Tomography (CT) System Se-
1.2 This practice applies to systems with a Digital Detector
lection
Array (DDA) and an X-ray source. It does not cover the use of
E1695 Test Method for Measurement of Computed Tomog-
isotope sources.
raphy (CT) System Performance
1.3 There are sections in this practice that may require
E1817 Practice for Controlling Quality of Radiological Ex-
agreement between the purchaser and the supplier, or specific
amination by Using Representative Quality Indicators
direction from the cognizant engineering organization (CEO).
(RQIs)
These items should be addressed in the purchase order or the
E2002 Practice for Determining Image Unsharpness and
contract. Generally, the items are application-specific, perfor-
Basic Spatial Resolution in Radiography and Radioscopy
mance related, or both.
E2339 Practice for Digital Imaging and Communication in
1.4 Applications for cone-beam CT are diverse. This prac- Nondestructive Evaluation (DICONDE)
E2597/E2597M Practice for Manufacturing Characterization
tice is not intended to be limiting or restrictive. Refer to Guide
E1441 for guidance on CT fundamentals and Guide E1672 for of Digital Detector Arrays
E2698 Practice for Radiographic Examination Using Digital
tradeoffs in selection of a CT system.
Detector Arrays
1.5 Units—The values stated in SI units are to be regarded
E2767 Practice for Digital Imaging and Communication in
as standard. No other units of measurement are included in this
Nondestructive Evaluation (DICONDE) for X-ray Com-
standard.
puted Tomography (CT) Test Methods
1.6 This standard does not purport to address all of the
E3147 Practice for Evaluating DICONDE Interoperability of
safety concerns associated with its use. It is the responsibility
Nondestructive Testing and Inspection Systems
of the user of this standard to establish appropriate safety,
2.2 ANSI Standards:
health, and environmental practices and determine the appli-
ANSI/ASNT CP 189 Standard for Qualification and Certifi-
cability of regulatory limitations prior to use. NCRP 144 or
cation of Nondestructive Testing Personnel
NIST Handbook 114, or both, may be used as guides to ensure
SNT-TC-1A Recommended Practice - Personnel Qualifica-
that radiographic procedures are performed so that personnel
tion and Certification in Nondestructive Testing
shall not receive a radiation dosage exceeding the maximum
2.3 ISO Standards:
permitted by the city, state, or national codes.
ISO 9712 Non-destructive Testing - Qualification and Cer-
1.7 This international standard was developed in accor-
tification of NDT Personnel
dance with internationally recognized principles on standard-
ization established in the Decision on Principles for the
Development of International Standards, Guides and Recom-
mendations issued by the World Trade Organization Technical For referenced ASTM standards, visit the ASTM website, www.astm.org, or
contact ASTM Customer Service at service@astm.org. For Annual Book of ASTM
Barriers to Trade (TBT) Committee.
Standards volume information, refer to the standard’s Document Summary page on
the ASTM website.
1 3
This practice is under the jurisdiction of ASTM Committee E07 on Nonde- Available from American National Standards Institute (ANSI), 25 W. 43rd St.,
structive Testing and is the direct responsibility of Subcommittee E07.01 on 4th Floor, New York, NY 10036, http://www.ansi.org.
Radiology (X and Gamma) Method. Available from International Organization for Standardization (ISO), ISO
Current edition approved Feb. 1, 2023. Published February 2023. DOI: 10.1520/ Central Secretariat, Chemin de Blandonnet 8, CP 401, 1214 Vernier, Geneva,
E3375-23. Switzerland, https://www.iso.org.
Copyright © ASTM International, 100 Barr Harbor Drive, PO Box C700, West Conshohocken, PA 19428-2959. United States
E3375 − 23
ISO/CIE 19476 Characterization of the Performance of Illu- 4. Significance and Use
minance Meters and Luminance Meters
4.1 The purpose of this practice is to establish instruction,
2.4 AIA Standard:
procedures, and equipment qualification to inspect a compo-
NAS 410 National Aerospace Standard Certification and
nent for specified discontinuities. This practice is written so it
Qualification of Nondestructive Testing Personnel
can be specified on the engineering drawing, specification, or
2.5 CEN Standard:
contract. This practice requires a detailed procedure delineat-
EN 4179 Aerospace Series - Qualification and Approval of
ing the technique or procedure requirements and shall be
Personnel for Non-destructive Testing
approved by the Cognizant Engineering Organization (CEO).
2.6 Government Standards:
4.2 The requirements in this practice shall be used when
NCRP 144 Radiation Protection for Particle Accelerator
7 placing a CT system into NDT service and establishing a
Facilities
baseline of system performance measures. Monitoring the
NIST Handbook 114 General Safety Standard for Installa-
system performance over time shall be performed, including
tions Using Non-Medical X-ray and Sealed Gamma Ray
detector correction procedures, performance measurements,
Sources, Energies up to 10 MeV
and system maintenance.
3. Terminology
4.3 For CT examinations where specified discontinuities are
not known/identified/requested/available (that is, engineering
3.1 Definitions—For definitions of terms related to CT used
analysis, engineering information only), portions of Section 7
in this practice, refer to Terminology E1316.
– 9 requirements do not necessarily apply. For these types of
3.2 Definitions of Terms Specific to This Standard:
examinations, the purchase order or contract shall specify the
3.2.1 cone beam, n—a beam of radiation that is restricted to
development of a specific procedure, approved by purchaser
two dimensions in an areal extent with the area covering the
and supplier, to specify the requirements of this practice to be
detector array.
incorporated into the examination.
3.2.2 contrast-detail-diagram (CDD), n—describes the
minimum relative contrast (in %) of a circular indication,
5. Basis of Application
required for the perception by human operators as a function of
5.1 The following items are subject to contractual agree-
the indication diameter in voxels in a 2D CT slice on a monitor
ment between the parties using or referencing this practice.
(see Guide E1441 and Test Method E1695).
5.1.1 Personnel Qualification—Personnel performing ex-
3.2.3 contrast discrimination function (CDF), n—describes
aminations to this practice shall be qualified in accordance with
the influence of image noise on the detectability of a feature in
NAS410, EN 4179, ANSI/ASNT CP 189, ISO 9712, or
an elsewhere homogeneous material neighborhood as a func-
SNT-TC-1A and certified by the employer or certifying agency
tion of the size of this feature in voxels.
as applicable. Other equivalent qualification documents may be
used when specified on the contract or purchase order. The
3.2.4 modulation transfer function (MTF), n—describes the
applicable revision shall be the latest unless otherwise specified
transfer of a spatial modulation in an image signal (relative
intensity variation, here by a CT system) as a function of the in the contractual agreement between parties.
5.1.2 If specified in the contractual agreement, NDT agen-
modulation’s spatial frequency
image
3.2.4.1 Discussion—SR in volume CT is correspond- cies shall be qualified and evaluated as described in Specifi-
b
cation E543. The applicable edition of Specification E543 shall
ing MTF 10 % established as per Test Method E1695. If
be specified in the contract.
calculated value is given in LP/mm, conversion in μm = ½ x [
5.1.3 Procedures and Techniques—The procedures and
(1 / (MTF value LP/mm) ]
techniques to be utilized shall be as specified in the contractual
3.2.5 purchaser, n—as used within this document, the pur-
agreement.
chaser of computed tomographic services refers to the entity
5.1.4 Reporting Criteria—Reporting criteria for the exami-
that requires the computed tomographic services; the purchaser
nation results shall be in accordance with this standard practice
may be a part of the same organization as the supplier, or an
unless otherwise specified.
outside organization.
5.1.5 Acceptance Criteria—Any acceptance criteria shall be
3.2.6 supplier, n—as used within this document, the supplier
specified in the contractual agreement.
of computed tomographic service refers to the entity that
physically provides the computed tomographic services; the
6. Equipment
supplier may be a part of the same organization as the
6.1 Many different CT system configurations are possible,
purchaser, or an outside organization.
and it is important that the user understands the advantages and
limitations of each (see Guide E1441 and Test Method E1695).
Available from Aerospace Industries Association (AIA), 1000 Wilson Blvd.,
6.2 All CT systems have four major subsystems: radiation
Suite 1700, Arlington, VA 22209, http://www.aia-aerospace.org.
source, radiation detectors, mechanical handling system, and
Available from European Committee for Standardization (CEN), Avenue
Marnix 17, B-1000, Brussels, Belgium, http://www.cen.eu.
computer system. The following represents considerations for
Available from National Council on Radiation Protection and Measurements
each subsystem for a CT examination.
(NCRP), https://ncrponline.org.
6.2.1 Source Setup—The radiation source shall be selected
Available from National Institute of Standards and Technology (NIST), 100
Bureau Dr., Stop 1070, Gaithersburg, MD 20899-1070, http://www.nist.gov. to provide the maximum signal-to-noise ratio (SNR) and
E3375 − 23
contrast to noise ratio (CNR) while maintaining the necessary reconstruction, visualization, and storage. The system shall
spatial resolution. See Guide E1441 for a detailed discussion. have the necessary storage and device interfaces to work with
the system provided.
6.2.2 Radiation Detection Systems—The detection system
shall consist of a two-dimensional array in an area detector. 6.2.4.1 Data Acquisition System—Very large data sets are
The more detectors used, the faster the required scan data can possible from high density pixel architectures with thousands
be collected; but there are important tradeoffs to be considered of views. Therefore, the computer system shall have enough
such as increased noise, increased data size, and decreased random-access memory (RAM) and hard drive space to ac-
collimation abilities to reduce scatter radiation capture. commodate and process this amount of data.
6.2.2.1 The detector cannot be operated without computing 6.2.4.2 Data Reconstruction System—The acquired scan
hardware and software for image acquisition. data may or may not be reconstructed on the same computer as
described in 6.2.4.1. It is preferred to also have Graphical
6.2.2.2 The acquisition software shall be capable of acquir-
Processing Units (GPUs) to accelerate the compute intensive
ing images projection-by-projection from the detector and
mathematical operations of CT reconstruction.
integrating or averaging frames, or both.
6.2.4.3 Visualization System—The reconstructed data may
6.2.2.3 The acquisition software shall perform a detector
or may not be viewed on the same computer(s) as described in
correction to correct any inhomogeneities of the detector.
6.2.4.1 and 6.2.4.2. This computer system shall be capable of
6.2.2.4 Users shall comply with the detector manufacturer’s
displaying the CT data as described by the written procedure.
requirements of temperatures and humidity conditions for both
operation and shipping.
6.3 System Software—Acquisition and reconstruction soft-
6.2.2.5 The detector shall be corrected using the manufac-
ware shall be established such that the scan data that is
turer’s recommendation both for frequency of detector correc-
collected, can be readily reconstructed either while the scan is
tion and the method used. Other detector correction methods
being collected, or very shortly after the scan is completed. If
are allowed as long as they are approved by the CEO.
these two software modules are located on two separate
computer systems, there shall be a high-speed link between the
6.2.2.6 The user shall ensure that all exposures are within
the linear operating range of the detector, using either infor- two.
mation obtained from the manufacturer or data obtained by the
6.3.1 Acquisition Software—Acquisition software shall be
user/CEO.
capable of modifying the projection data such as normalizing
6.2.3 Manipulation System—The manipulation system has pixel gain and offset levels, and bad pixel correction.
the function of holding the test object to provide the necessary
6.3.2 Reconstruction Software—Reconstruction software
range of motions to position the test object between the
shall include the reconstruction kernel, beam hardening
radiation source and detector. This practice applies to scan
corrections, reconstruction filters.
motion geometries that are rotate-only motion or rotate-
6.4 Image Display—The function of the image display is to
translate (helical). Other types of scan motion geometries may
convey derived information (that is, an image) of the test object
be used as agreed upon between user and CEO.
to the system operator. For manual evaluation systems, the
6.2.3.1 Users shall comply with the handling system manu-
displayed image is used as the basis for accepting or rejecting
facturer’s requirements of weight, size, temperatures, and
the test object, subject to the operator’s interpretation of the CT
humidity conditions for both operation and shipping.
data.
6.2.3.2 The handling system shall be calibrated using the
6.4.1 Dust and dirt need to be kept to a minimum and the
manufacturer’s recommendation both for frequency of calibra-
image display face needs to be cleaned often to prevent
tion and the method used. Other calibration methods are
interference with interpretation.
allowed as long as they are approved by the CEO.
6.5 Data Storage Medium and Data Transfer—A separate
6.2.3.3 The geometric accuracy of the system shall be
data storage system may be required to manage the massive
checked to ensure the source to detector distance (SDD) and
amount of data that is collected over time. This storage system
the source to object distance (SOD) relation is within tolerance.
architecture is dependent on the amount of data and time that
A ball bar or other device with a known distance between at
the data, be it the projection views or the reconstructed
least two points may be used to calibrate the geometric
volumes, or both, and associated technique data need to be
accuracy. The resulting image measurement shall be within an
stored. This storage system is also dependent on whether the
established tolerance of the nominal geometry of the ball bar
purchaser will manage the archival of data. If this is the case,
and approved by the CEO.
there shall be an agreement between parties on how the data is
6.2.3.4 The user shall ensure that all exposures are within
transmitted to the purchaser. The reproduction quality of the
the X-ray cone beam envelope of the source-handling system,
archival method shall be sufficient to demonstrate the same
using either information obtained from the manufacturer or
image quality as was used to qualify the CT technique. For
data obtained by the user/CEO. Source-handling systems that
systems that are intended to be DICONDE compliant, the
allow for offset scanning large components outside of the
software shall be capable of storing and transferring data in
X-ray cone beam may be used as agreed upon by the user and
accordance with Practices E2339, E3147, and E2767.
CEO.
6.2.4 Computer System(s)—The computer system provides 6.6 Image Quality Indicators (IQIs) and Representative
the operator interface and performs the tasks of acquisition, Quality Indicators (RQIs)—IQIs or RQIs shall be used to
E3375 − 23
demonstrate the CT system’s ability to detect discontinuities, 7. Equipment Qualification and Long-term Stability Tests
indications, or flaws and to monitor the performance of a CT
7.1 Documentation of the initial equipment qualification
system over time.
shall be kept on file for the life of the system as well as all
6.6.1 RQIs—RQIs are used to validate the performance of a
subsequent re-qualifications.
system to detect indications. RQIs shall be used as specified by
7.1.1 Initial system qualification (or detector replacement)
detector
the purchaser in the contractual agreement between purchaser
shall include: a SR measurement (see Practice E2597/
b
and supplier in accordance with Practice E1817. A discussion
E2597M).
on the use of RQIs is found in 8.3.
7.1.2 An overall system requalification shall be required
6.6.2 Volumetric IQIs—In some cases, it is impossible to
when:
fabricate the appropriate RQIs. Alternatively, additional phan-
(1) The DDA, X-ray generator, X-ray tube, or other com-
toms may be needed to determine the quality of the CT system
ponent(s) affecting image quality is repaired or replaced.
to detect the features of interest in each component. In these
(2) Changes are made to image acquisition software, re-
cases, a volumetric IQI may be fabricated representing the
construction software, or processing software where any of
thickness of the component and the indications to be detected
these has an impact on image or measurement quality.
in that component. The RQI indication requirements of 8.3
(3) Image display monitors are repaired or replaced.
shall be met in developing the Volumetric IQI. The placement
(4) The system is moved.
of the IQI shall be as agreed upon between the user and the
7.2 For initial equipment qualification, long-term stability
CEO.
tests (as defined in Table 1) and a baseline shall be established.
6.6.3 E1695 Rods—Rod-like hardware is defined in Test
7.2.1 The data for qualification shall be acquired at a
Method E1695 and referred to as cylinders to measure the
frequency defined by contracting parties to assure consistent
Modulation Transfer Function
...